2014 年 22 巻 2 号 p. 176-182
Because magnetic particle testing (MT) can detect microcracks by a simplified method, it is applied in non-destructive inspections of ferromagnetic materials in various industrial fields. Recently, establishing a technology that quantitatively evaluates crack shapes as well as detects cracks with high-precision has become an important topic in the non-destructive inspection. We consider developing such a quantitative evaluation technique that employs magnetic particle pattern of a crack in MT. In this research, the process of magnetic particle adherence to a crack was observed with a high-speed video camera and the change in the magnetic particle amount was evaluated at each instant. In addition, the technique for evaluating small magnetic flux leakage (MFL) density accurately was discussed with the measurement and the numerical analysis. From these results, the relationship between the MFL density and the magnetic particle amount was evaluated.